Summary notes of the LCU meeting on 14/05/2012

Present: HB, RdM, LD, SF, MF, MG, EM, MS, RT, RV

Report from meetings

• SLM and general information -> MG
  The meeting was exceptionally scheduled on Monday to avoid a clash with the presentation of the IPAC'12 talks this Tuesday in a special ATS seminar.
  The LHC progress after the 1 week stop was slow for several reasons : several cryogenic faults, more halo and losses during the squeeze. Losses were predominantly on beam2. While the LHC is mostly rather beam1/beam2 symmetric, we also know of some parameters like the bare machine coupling which are worse for beam 2. The situation in the LHC is currently improving and will be reviewed this week in the LMC.
  The approval status of our IPAC'12 papers can be seen on the page AllContributions.aspx.
  Approved contributions should be submitted to the conference site. The deadline is Wednesday night.
  The departmental report for 2011 is being written. It is edited by Gianluigi and should be ready in the middle of next week (the IPAC'12 week).
  A group meeting and lunch-barbecue is scheduled for the 18 June.

MAD-X status -> LD
A module keeper meeting was organized recently but not too well attended due to the rush in IPAC paper preparation. Another meeting will be organized after IPAC. Two levels of MAD-X testing are foreseen, the first by the module keepers followed by a second more general test. A tool was made which can automatically compare the test results with references. The same tool will also be used for PLACET validation. Laurent is also working on an improved physics understanding and documentation and plans to set up a physics guide based on what was started for MAD-8 many years ago. He asked for help to get access to the source of the MAD-8 physics guide and it was suggested to contact Eberhard Keil.
Massimo said that slicing was reviewed for IPAC and that Helmut will upgrade MAKETHIN to allow for TEAPOT slicing for more than 4 slices per magnet.

Impact of the B6 and B10 field imperfections in the triples at injection for the HL-LHC upgrade -> RdM (slides)
The new Nb3Sn cables currently studied for LHC triplet upgrade have a larger filament size than the cables used in the current magnets. This is expected to increase persistent current effects at injection. In addition, there are plans to decrease beta* at injection by a factor of two  (from 11m to 5.5 m) and would make the LHC more sensitive to field imperfections. RdM made tracking studies over 1.e5 turns for various field imperfections and determined the dynamic apertures (DA). He finds that a b6 component of -60 units results in a visible DA reduction while -20 units should be tolerable. Similarly, he starts to see a visible degradation in DA for b10 of 10 units or larger.
He also checked the situation at top energy, were magnet imperfections become significant due to the large crossing angle with significant feed-down effects. He looked at detuning with action and showed the footprints expected with imperfections. Some compensation of imperfections can be expected between IP1 and IP5 from having the crossing angle in opposite planes.

Last update: 17-May-2012

MG & HB

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